Transformative ecological and human impacts from climate change and diminished sea ice in the northern Bering Sea

Abstract Our goal is to tie climate scale mete o rology to regional physics and ecosystem changes, and on to human impacts. There was record minimum sea-ice cover during winter 2018 and 2019 in the Bering Sea, with continuing multi-year impacts on the marine ecosystem and human activities. The back-to-back sea-ice minimums during 2018 and 2019 were certainly unexpected, given the normal large year-to-year variability of storms for the northern Bering Sea. Ecological shifts indicated reorganization of the northern marine food web that included loss of sea-ice algae and young crabs, and predatory cod and pollock moving north impacting lower trophic levels. Possible direct impacts from sea-ice loss and warmer temperatures included increased seabird and ice-associated seal emaciation and mortality, and increased harmful algal blooms. These changes affected regional food security, human/wildlife health, cultural activities, and marine wildlife conservation. Global warming initiated these events through a weakened atmospheric Arctic Front that promotes a self-reinforcing cycle of sea-ice loss, warmer temperatures, southerly winds and a wavy jet stream. Resulting impacts to livelihoods in the northern Bering Sea were commercial and non-commercial subsistence acquisition of essential marine resources for sale and direct consumption. Interannual variability is still important; during 2022 and 2023 the Aleutian Low pressure system was regionally dominant and sea ice was near the climatological average. Projections for the next decades are for an increasing frequency of low sea-ice years and a continuing ecosystem transition impacting essential marine wildlife resources and residents of the coastal northern Bering Sea.